Helllo
Today I changed the valve springs of my engine dz160,
I noticed that have six holes around the inlet valve in the cylinder head ( Attached Image )
My question what these holes are used ?
Thanks
kobi

The area under the valve cover is used as an air plenum or chamber to store the charge untill the intake valve opens.

Thanks
But I do not really understand you

You should be able to see the back of the intake valve through those holes. When the intake valve opens, air from the rocker cover flows through those holes past the intake valve into the cylinder.

At high throttle settings, the air in the intake tube and rocker cover is at a pressure higher than the air outside because it's been "pumped up" a bit already during the previous power stroke by the downgoing piston and sealed off to hold that pressure with a disk valve.

I wonder if "stuffing" the rocker cover would increase the supercharging effect?

Thanks
bjr_93tz